For producing a molded part in plastic material, heated plastic material in a liquid or viscous state, is introduced into a mold so as to assume the shape of the mold, and the plastic material then cools and solidifies. It thus retains the shape which was given to it in the mold.
During the cooling of the molded part, it is possible that shrinkage of the plastic material occurs, i.e. a contraction of the molded part. The result of this may be that the molded part after cooling does not have the required dimensions. This shrinkage phenomenon is all the more sensitive since the plastic material part has great dimensions.
It is possible to dimension the mold according to the expected shrinkage so that the molded part after cooling has the required dimensions. Nevertheless the shrinkage of a molded part may also change over time depending on the molding parameters like pressure or temperature. This shrinkage is difficult to anticipate, which complicates the manufacturing of the molded part.
It is possible to use a metrological instrument specifically developed for the molded part and comprising a structure allowing the part to be received in a determined position and on which are mounted sensors for measuring predefined dimensions of the molded part repeatedly and accurately. Nevertheless, such instrument is expensive, cumbersome and time-consuming for application.